Supernova Brighter And More Massive Than Any Yet Recorded – Identified

Eddie Gonzales Jr. – MessageToEagle.com – A supernova at least twice as bright and energetic, and likely much more massive than any yet recorded has been identified by an international team of astronomers, led by the University of Birmingham.

The supernova, dubbed SN2016aps, could be an example of an extremely rare ‘pulsational pair-instability’ supernova, possibly formed from two massive stars that merged before the explosion.

Artist’s impression of a supernova. Credit: Aaron Geller, Northwestern University

“We can measure supernovae using two scales – the total energy of the explosion, and the amount of that energy that is emitted as observable light, or radiation, ” Dr. Matt Nicholl, of the School of Physics and Astronomy and the Institute of Gravitational Wave Astronomy at the University of Birmingham, said in a press release.

“In a typical supernova, the radiation is less than 1 percent of the total energy. But in SN2016aps, we found the radiation was five times the explosion energy of a normal-sized supernova. This is the most light we have ever seen emitted by a supernova.”

In order to become this bright, the explosion must have been much more energetic than usual. By examining the light spectrum, the team were able to show that the explosion was powered by a collision between the supernova and a massive shell of gas, shed by the star in the years before it exploded.

“While many supernovae are discovered every night, most are in massive galaxies,” said Dr Peter Blanchard, from Northwestern University and a co-author on the study. “This one immediately stood out for further observations because it seemed to be in the middle of nowhere. We weren’t able to see the galaxy where this star was born until after the supernova light had faded.”

The team observed the explosion for two years until it faded to 1 percent of its peak brightness, and  calculated the mass of the supernova was between 50 to 100 times greater than our sun (solar masses). Typically supernovae have masses of between 8 and 15 solar masses.

“Stars with extremely large mass undergo violent pulsations before they die, shaking off a giant gas shell. This can be powered by a process called the pair-instability, which has been a topic of speculation for physicists for the last 50 years,” says Dr. Nicholl. “If the supernova gets the timing right, it can catch up to this shell and release a huge amount of energy in the collision. We think this is one of the most compelling candidates for this process yet observed, and probably the most massive.”

“SN2016aps also contained another puzzle,” added Dr Nicholl. “The gas we detected was mostly hydrogen – but such a massive star would usually have lost all of its hydrogen via stellar winds long before it started pulsating. One explanation is that two slightly less massive stars of around, say 60 solar masses, had merged before the explosion. The lower mass stars hold onto their hydrogen for longer, while their combined mass is high enough to trigger the pair-instability.”

“Finding this extraordinary supernova couldn’t have come at a better time,” according to Professor Edo Berger, a co-author from Harvard University. “Now that we know such energetic explosions occur in nature, NASA’s new James Webb Space Telescope will be able to see similar events so far away that we can look back in time to the deaths of the very first stars in the Universe.”

Paper

Written by Eddie Gonzales Jr. – MessageToEagle.com Staff